Error CS0117: `unityeditorinternal.internaleditorutility' does not contain a definition for `addscriptcomponentunchecked'

AssetDatabase.Refresh();
		AssetDatabase.ImportAsset( path, ImportAssetOptions.ForceSynchronousImport );

		var gameObj = target.gameObject;
		var script = AssetDatabase.LoadAssetAtPath( path.MakeRelativePath(), typeof( MonoScript ) ) as MonoScript;
		InternalEditorUtility.AddScriptComponentUnchecked( gameObj, script );

		#region Delayed execution

		// Declared with null value to eliminate "uninitialized variable" 
		// compiler error in lambda below.
		EditorApplication.CallbackFunction callback = null;